DE19846650A1 - Aqueous powder paint slurry, useful for the coating of motor vehicle bodies, comprises a hydroxyl group binding agent and a polyisocyanate crosslinking agent with stabilized surface isocyanate groups. - Google Patents

Abstract

A powder paint slurry comprises a hydroxyl group binding agent, a polyisocyanate cross-linking agent and water whereby isocyanate groups on the surface of the particles are stabilized by a deactivating agent. A powder paint slurry (I), preferably a clear lacquer powder slurry contains (A) a hydroxyl group containing binding agent, (B) a polyisocyanate cross-linking agent and water. (A) and (B) are homogenized such that no less than 30(60), preferably 90 wt.% of (B) is dispersed or dissolved in (A). Isocyanate groups on the surface of particles of (B) and (A) containing (B) are stabilized by means of a deactivating agent added to the aqueous phase. Independent claims are included for a process for the production of (I) by homogenization of (A) and (B), grinding of the resulting mixture and wet grinding of the resulting powder to an average particle size of less than 10 microns.

Description

The present invention relates to a powder coating slurry, in particular a powder clear paint slurry containing at least one hydroxyl-containing binder A and a ver wetting agent B with free isocyanate groups and water, the components being microencapsulated particles are present. The inventions further relates to a method for Production of such a powder coating slurry and its use for production coated substrates.

In the context of the present invention, a dispersion is a powder coating slurry to understand particles of solid film-forming coating agents in water. You can Coating agent particles may be the same or different in their composition. At for example, the particles can be either a binder A or a binder mixture A. and also contain a crosslinking agent mixture B. Alternatively, part of the Coating agent particles essentially from binder A or the binder Mixture A and another part essentially from crosslinking agent B or Crosslinking agents B exist. The coating agent particles can also be conventional and known additives contain, unless they are separately dispersed or dissolved in water available.

A wide variety of coating compositions are known for the production of clearcoats. Clear coats of high resistance to chemicals, solvents, acid rain and Weathering results from coating agents based on hydroxyl groups Polyacrylates (polyhydroxy polyacrylates) obtained with free polyisocyanates be networked. On the one hand, it is disadvantageous that they are two-component systems and on the other hand that the proportion of organic solvents in the range of 40 to 45 wt .-% is.  

To avoid solvent emissions, various powder clear coats have been developed been wrapped.

So are powder clearcoats based on hydroxyl-containing polymers and capped Polyisocyanates are known, epsilon-caprolactam and / or being the capping agent Ketoxime can be used. Disadvantages of these powder coatings are the special requirement Application equipment, contamination sensitivity, the need for high layer thick for usable flow and high baking temperatures. The special requirement whose application devices interfere with the integration of powder coating technologies in be existing painting lines for economic and technological reasons, esp special because a partial reinstallation of the painting lines is required. The exploration The high layer thickness results from the relatively large particles of approx. 25 microns and is annoying for economic and weight reasons.

Furthermore, powder clearcoats are based on polyacrylates containing epoxy groups, which are crosslinkable with polycarboxylic acids or their anhydrides. They also show that disadvantages mentioned above. In addition, the durability of solvent-based two-component clear coats achieved. The same applies to the known ones Powder clearcoats based on polyacrylates and hydroxyl groups Polyisocyanates according to German patent DE-A-44 06 157.

Powder coating slurries are for example from the patents DE-A-196 13 554 and WO 96/32452 known. They are based on epoxy group-containing polyacrylates, which with Polycarboxylic acids are crosslinked. These well-known powder coating slurries are on convents tional application devices can be processed and have practically no organic Solvent. However, they can be further optimized so that the result is provided clearcoats achieve the property profile of the two-component clearcoats.

As far as the term "free isocyanate groups" is concerned, are within the scope of the present inventions the following explanations and definitions are required. A polyisocyanate Sen isocyanate groups are mainly protected with a capping agent  practically no more free isocyanate groups. The use of such capped poly However, isocyanates in coating compositions have the disadvantage that when the Isocyanate groups when stoving to a considerable extent resulting products are released, which for environmental reasons is disadvantageous and often leads to lower cooker limits. The latter means that in The coatings form gas bubbles when baked, if a certain layer thickness is exceeded. Therefore, polyisocyanates have been developed, which are discrete Particles are present and their polyisocyanate groups arranged on the particle surface have been reacted with a deactivating agent. The concept of implementation not only includes chemical reactions of the surface isocyanate groups with the deactivating agent, but also a physical blocking of the Surface of the particles, for example, by physisorption or chemisorption. in the In any case, the isocyanate groups are freely available in volume of the particles. The share of with a deactivating agent converted isocyanate groups to the free isocyanate groups the volume of a particle is usually less than 0.3, usually even considerably less than 0.1. Therefore, such so-called microencapsulated polyisocyanates become uncapped Counted polyisocyanates. Becomes a microencapsulated polyisocyanate with a binder heated, the polyisocyanate particles and those previously purely geometric and / or melt Physically protected volume isocyanate groups are used for the Crosslinking reactions accessible and can crosslink the binder.

Microencapsulation is known per se, for example in the patents DE- A-32 28 670, DE-A-32 28 724, DE-A-31 12 054, DE-A-32 30 757, US-A-4, 888,124 or EP-A-0 510 476. Here i. d. R. the solid, finely ground polyisocyanate in dispersed a liquid polyol, which is also the reactive counter component for the Networking forms. These systems are used to manufacture foams or sub soil protection. For the production of paints with high surface requirements course and gloss are not suitable.

The object of the present invention is to provide a one-component lacquer, in particular a One-component clearcoat to find, which in particular provides clearcoats that from  Clear varnishes produced in two-component varnishes, especially in gloss, are on a par, and which can be applied with the usual spray application devices and has just as low pollutant emissions as powder clearcoats. In addition, should the one-component paint also has excellent storage stability and a good flow with a small layer thickness.

Accordingly, the new powder coating slurry, in particular the new powder clear coating slurry, was found comprising at least one hydroxyl-containing binder A, at least one polyisocyanate as crosslinking agent B and water, where

• 1. the hydroxyl-containing binder A and the polyisocyanate B are so homogeneous are not less than 30, preferably not less than 60 and in particular not less than 90 wt .-% of the polyisocyanate B in the Particles containing binder A are dispersed or dissolved and
• 2. the particles of the. Which may still be in the aqueous phase Polyisocyanate B and the particles containing the binder A and the polyisocyanate B contain, via the isocyanate groups present on their surface by means of a the deactivating agent added to the aqueous phase are stabilized.

Surprisingly, uncapped polyisocyanates B together with a Binder A are dispersed in water so as to form a storage-stable powder coating slurry form when the microencapsulation of the particles in the aqueous phase by means of Deactivating agent is carried out. Since the deactivation mostly not with the binder A is carried out, coatings, especially clearcoats, with very good flow and high gloss even with a layer that is atypically low for powder coatings be obtained thick. Those produced from the powder coating slurry according to the invention Coatings and clear coats have resistance properties which are similar to those of Reach clearcoats that have been made from two-component systems. After all, it is practically emission-free because organic solvents, if  at all, only in very small amounts in the powder coating slurry according to the invention are included.

It is essential for the powder coating slurry according to the invention that the homogenization is so goes far that not less than 30, preferably not less than 60 and especially not less than 90% by weight of the polyisocyanate B in the discrete binder particles A distributed, d. H. are dissolved or dispersed.

According to the invention, the polyisocyanates B together with the binders A are in the Particles. For practical reasons, however, less than 100% by weight of the Polyisocyanates B are present in the particles in addition to the binders A. In this case the polyisocyanates B form particles which are present as a separate discrete phase. It is essential that not less than 30, preferably not less than 60 and in particular containing not less than 90% by weight of the polyisocyanates B in the particles are in which the binders A are present. In other words, at most 70, preferably at most 40 and in particular at most 10% of the polyisocyanates B. exist as separate discrete particles.

According to the invention, it is advantageous if the binders A and crosslinking agents B in a ratio that the molar ratio of hydroxyl Groups to isocyanate groups is 0.6: 1 to 1: 1.4, in particular 0.8: 1 to 1: 1.2.

In addition, conventional additives, in particular degassing agents, leveling agents, Light stabilizers such as UV absorbers and radical scavengers, defoamers, Antioxidants and stabilizers may be present, with the additives either in the Particles and / or the aqueous phase are present. Furthermore, at least one Catalyst for the reaction of the hydroxyl groups with the isocyanate groups.

In a preferred embodiment, binder A contains:

• a) 50-100% by weight, preferably 66-100% by weight, of a polyhydroxy polyacrylate,  
• b) 0-50% by weight, preferably 0.1 to 34% by weight, of one or more of a) different binders from the group "polyols, polyhydroxypolyurethanes, polyhydroxypolyesters, polyepoxides". The polyhydroxy polyacrylate a) can be obtained by reacting
  • a1) 7 to 60% by weight of hydroxyalkyl (meth) acrylates with primary, secondary and / or tertiary OH groups,
  • a2) 40-93% by weight (cyclo) alkyl ester of (meth) acrylic acid with 1 to 18 carbon atoms in the (cyclo) alkyl radical,
  • a3) 0-5% by weight (meth) acrylic acid,
  • a4) 0-30% by weight, preferably 0-10% by weight, multiple (meth) acrylic acid esters of polyalcohols,
  • a5) 0-40% by weight, preferably 0-35% by weight of comonomers different from a1 to a4,

the sum of the parts by weight of components a1 to a5 being 100%, the Component a1 is selected with the proviso that at least 40% of the OH groups of the Polyhydroxypolyacrylates a are bound to secondary or tertiary carbon atoms and wherein the polyhydroxy polyacrylate a has an OH number of 30 to 200, preferably 70 to 170, an acid number from 0 to 50, preferably from 0 to 35, an average molecular weight (Number average), determined by means of the GPC method against polystyrene standard), from 1500 to 30000, preferably from 1700 to 18000, and a glass transition temperature from 40 to 85 ° C, preferably from 45 to 75 ° C.

Crosslinking agent B preferably has an NCO content of 5.0 to 30% by weight, preferably from 12 to 23% by weight, with an average NCO functionality of at least at least 2.1, preferably at least 2.4, and containing monomeric diisocyanates with a molecular weight of less than 300 of less than 1.5% by weight. The glass over transition temperature is 40 to 150 ° C, preferably 50 to 135 ° C (measured by means of Differential thermal analysis, DTA).

In a development of the invention, one or more of the networking can medium B various crosslinking agents from the group "amino resins, carbamate resins,  masked polyisocyanates "in an amount of up to 60% by weight of crosslinking agent B be included.

One or more substances from the group is preferably used as the deactivating agent "Alcohols, OH-functional polyethers, monoamines, polyamines, OH-functional amines, NH-functional polyethers, OH- and NH-functional polyethers "used.

Finally, the invention comprises the use of the powder clear lacquer according to the invention. Slurry for the production of a coated substrate, in particular a motor vehicle body or a motor vehicle body part, on the substrate, if necessary after applying a primer and / or a filler, a decorative top coat is applied and after predrying then the powder clearcoat slurry with conventional spray application equipment is applied and the topcoat and the powder clearcoat optionally after another Predrying can be baked together.

The hydroxyl groups of binder component A advantageously consist of min at least 40, preferably at least 50 and particularly preferably 90 to 100% secondary and / or tertiary carbon atoms bound hydroxyl groups and other, d. H. up to a maximum of 50%, preferably up to a maximum of 30% and particularly preferred up to a maximum of 10% of alcoholic hydroxyl bound to primary carbon atoms groups.

As binder component A are polyhydroxypolyacrylates, polyhydroxypolyurethanes or polyhydroxy polyester.

The polyhydroxypolyurethanes are obtained by reacting urethane group-free polyols (a) with diisocyanates (b) while maintaining an OHINCO equivalent ratio of 1.1: 1 to 10: 1, preferably 1.2: 1 to 2: 1, particularly preferably 1, 3: 1 to 1.8: 1, at temperatures of generally 40 to 200 ° C., preferably from 60 to 160 ° C., with the proviso that the equivalent ratio of primary bonded OH groups in the starting polyols (a) to NCO groups of the diisocyanates (b) OH _prim. / NCO <1.

Polyols (a) suitable for the construction of the polyhydroxypolyurethanes are:

• 1. aliphatic or cycloaliphatic, optionally containing ether groups more valuable alcohols in the molecular weight range 62 to 400, preferably 76 to 261,
• 2. Polyhydroxyl compounds containing ester groups of a medium, from function lity and OH number predictable molecular weight from 134 to 2000, preferably from 176 to 1500, and an average OH functionality of 2.0 to 4.0 and, if appropriate, but less preferred
• 3. further ester groups containing polyhydroxyl compounds of a medium size Functionality and OH number of calculable molecular weight above 2000 to 10,000, preferably up to 5000 and OH numbers between 20 and 200, preferably between 40 and 160.

As a rule, the incorporation of the secondary and / or tertiary-bonded OH groups Group (a1) polyols used. Are suitable for. B. 1,2-propanediol, 1,2-, 1,3- and 2,3- Butanediol, 3-methyl-1,3-butanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 1,2-octanediol, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,2- Hexadecanediol, 1,12-octadecanediol, 1,2- and 1,4-cyclohexanediol, 2,2,4,4-tetramethyl-1,3- cyclobutanediol, 2,2-bis (4-hydroxycyclohexyl) propane, glycerin and 1,2,6-hexanetriol. As Further polyols of group (a1) can optionally also include polyols exclusively primary bound OH groups are used, if at all, however, as a rule in minor proportions. Suitable for this are, for. B. 1,2-ethanediol, 1,3-propanediol, 1,4- Butanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexanedimethanol, 1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, penta erythritol or 1,3,5-tris (2-hydroxyethyl) isocyanurate.

In the ester groups used for the production of the polyhydroxypolyurethanes Send polyhydroxyl compounds (a2) are known ester alcohols or ester alcohol mixtures, such as those obtained by reacting polyvalent ones Alcohols with insufficient amounts of polyvalent carboxylic acids, corresponding Carboxylic anhydrides, corresponding polycarboxylic acid esters of lower alcohols  or can be produced by reacting polyhydric alcohols with lactones. For Production of the ester alcohols (a2) suitable polyhydric alcohols are in particular those of the molecular weight range 62 to 400, as exemplified under point (a1) and with such primary, secondary, or tertiary OH groups apply that the polyhydroxy ultimately obtained polyurethane the required content of secondary and / or tertiary bound Have hydroxyl groups. The acids used to make the ester alcohols or acid derivatives can be aliphatic, cycloaliphatic, aromatic and / or hetero be aromatic in nature and optionally, e.g. B. by halogen atoms, substituted and / or be unsaturated. Examples of suitable acids are, for example, polyvalent carboxylic acids of the molecular weight range 118 to 300 or their derivatives such as Succinic acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, trimellitic acid, Phthalic anhydride, tetrahydrophthalic acid, maleic acid, maleic anhydride, dimers and trimeric fatty acids, dimethyl terephthalate and bis-glycol terephthalate. Any mixtures of examples can also be used to prepare the ester alcohols starting compounds mentioned are used. Their manufacture is used e.g. B. in Houben Weyl, MV / 2, pp. 1-46. Preference is given to producing the poly hydroxypolyurethanes as starting component (a2) but also ester polyols are used, as they are known from lactones and simple polyhydric alcohols as Have starter molecules made with a ring opening, provided that they are sufficient amounts of structural components with secondary and / or tertiary bound Hydroxyl groups also used to the relevant to the invention Conditions to match. Suitable lactones for the preparation of these ester polyols are for example β-propiolactone, γ-butyrolactone, δ-valerolactone and δ-caprolactone, 3,5,5- and 3,3,5-triethylcaprolactone or any mixture of such lactones. As Starter molecules serve, for example, the polyvalent ones mentioned above as examples Alcohols (a1) of the molecular weight range 62 to 400 or any mixtures thereof Alcohols. The preferred ester polyols are generally prepared in counter were from catalysts such as Lewis or Brönstedt acids, organic tin or titanium compounds at temperatures of 20 to 200 ° C, preferably 50 to 160 ° C.  

The esters which can optionally also be used to prepare the polyhydroxypolyurethanes group-containing polyhydroxyl compounds (a3) of a higher molecular weight range are described in principle under (a2) from the same output ver bindings made.

Preferred components (a1) are 1,2-propanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3- hexanediol and 2,2,4-trimethyl-1,3-pentanediol. Preferred components (a2) are those based on 1,6-hexanediol, 1,1,1-trimethylolpropane and 6-caprolactone, isophthalic acid, Phthalic anhydride, tetrahydrophthalic acid, maleic anhydride and adipic acid. Components (a3) are used, if at all, only in minor quantities.

Diisocyanates (b) suitable for building up the polyhydroxypolyurethanes are in principle those of the molecular weight range 140 to 300 with (cyclo) aliphatically bound Isocyanate groups, such as. B. 1,4-diisocyanatobutane, 1,6-diisocyanatohexane (HDI), 2- Methyl 1,5-diisocyanatopentane, 2,2-dimethyl-1,5-diisocyanatopentane, 2,2,4- or 2,4,4- Trimethyl-1,6-diisocyanatohexane, 1,10-diisocyanatodecane, 1,3- and 1,4-diisocyanato cyclohexane, 2- or 4-methyl-1,3-diisocyanatocyclohexane, 1,3- or 1,4-bis- (2- isocyanatoprop-2-yl) benzene, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI) and 4'4'-diisocyanatodicyclohexylmethane (HMDI). Preferred used Diisocyanates (b) are HDI, IPDI and HMDI, the latter being very particularly preferred.

Any mixtures of polyols (a) can be reacted with any mixtures of diisocyanates (b) to produce the polyhydroxypolyurethanes. In general, the polyols (a) are used as mixtures, selected from the group consisting of the polyols (a1) and the polyols (a2) containing ester groups, optionally also (a3), the composition being chosen so that the abovementioned conditions of OH / NCO ratio and the OH _prim. / NCO ratio are observed.

Mixtures of polyols (a) suitable for the production of the polyhydroxypolyurethanes result, for example, even if the more used as the starting material valuable alcohols (a1) of the type mentioned by way of example with deficient amounts of acid  Ren or acid derivatives of the type mentioned by way of example only partially in ester alcohols (a2) be transferred.

In addition to the restrictions mentioned, the starting materials (a) and (b) are also selected such that polyhydroxypolyurethanes within the OH number range mentioned above for the polyol components a2) are preferably resins which are solid at room temperature and have the glass transition temperatures T _g of 30 to 120, preferably 40 to 100 ° C arise.

The polyhydroxypolyurethanes suitable according to the invention can be prepared in one step or in several stages. So the total amount of polyols (a) used can be submitted and reacted with the diisocyanates (b). But you can also z. B. with a Subset of the polyols (a1) to the diisocyanates (b) under mild reaction conditions sec / tert Implement OH and NCO group-containing pre-adducts and then z. B. the primary Allow polyols (a2) containing OH groups to react. In another out In the embodiment, polyols (a1) and / or (a2) containing primary OH groups can also be used. are reacted with excess diisocyanate (b) to give NCO-terminated prepolymers and subsequently by reaction with polyols (a1) and / or optionally also (a2), the sec. and / or tert. OH groups are introduced. The one required for urethane formation Reaction temperature is 20 to 200 ° C, preferably 40 to 160 ° C, particularly preferably at 40 to 120 ° C. The reaction is preferably carried out without a solvent guided. To accelerate the urethanization reaction, the usual from the Known catalysts used in polyurethane chemistry, for example tert. Amines such as triethylamine, pyridine, methylpyridine, benzyldimethylamine, N, N-endoethylene piperazine, N-methylpiperidine, pentamethyldiethylenetriamine, N, N-dimethylaminocyclohexane, N, N'- Dimethylpiperazine or metal salts such as iron (II) chloride, zinc chloride, zinc 2-ethylcaproate, Tin (II) -2-ethyl caproate, dibutyltin (IV) dilaurate and molybdenum glycolate. This Catalysts are preferably used in amounts of 0.001 to 2.0% by weight 0.01 to 0.5% by weight. based on the total amount of output connection used applications. Although the production of the polyhydroxypolyurethanes without Solvent in the melt is preferred, in some cases the use of inert  Solvent. In these cases, a suitable one then closes Evaporation process to free the compounds obtained from the solvent and isolate the solid resins. Suitable evaporation processes are e.g. B. such as listed below in the production of suitable polyhydroxy polyacrylates.

The polyhydroxy polyacrylates to be used as possible binder component A correspond in terms of the type of binding of the hydroxyl groups, their OH number and their glass transition temperature to the conditions generally stated above for component A. Such polyhydroxy polyacrylates are accessible in various ways:

• 1. Use of hydroxypropyl (meth) acrylate (in the addition of propylene oxide (Meth) acrylic acid isomer mixture with approx. 75 secondary and approx. 25 primary bound OH groups) as hydroxy-functional comonomers in the preparation of Polyacrylates.

Three types of monomers are generally used in the production of such polyacrylates used, namely (i) 7 to 60 parts by weight of hydroxypropyl (meth) acrylate, (ii) 93 to 40 parts by weight of non-functional olefinically unsaturated compounds and (iii) 0 to 5 parts by weight of carboxy-functional olefinically unsaturated compounds, the Sum of the parts by weight of components (i) to (iii) is 100. For the monomers (ii) it is for example aromatics such. B. styrene, vinyl toluene, α-methylstyrene and α-ethylstyrene; to (cyclo) alkyl esters of acrylic or methacrylic acid with 2 to 18 carbon atoms in the (cyclo) alkyl radical, such as. B. methyl (meth) acrylate, Ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate. n-butyl (meth) acrylate, Isobutyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Cyclohexyl (meth) acrylate, neopentyl (meth) acrylate, isobornyl methacrylate, Benzyl methacrylate, phenylethyl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate and Stearyl methacrylate, to dialkyl esters of maleic and / or fumaric acid with 1 to 12 Carbon atoms in the alkyl radical, such as. B. dimethyl maleate, maleic acid diethyl ester, maleic acid di-n-propyl ester, maleic acid diisopropyl ester, maleic acid di-n- butyl ester, maleic acid diisobutyl ester, maleic acid di-tert.-butyl ester, maleic acid di-2-  ethylhexyl ester, maleic acid dicyclohexyl ester and the corresponding fumaric acid esters. At the monomers (iii) are, for example, acrylic acid, methacrylic acid and Maleic acid or fumaric acid semiesters with 1 to 12 carbon atoms in the alcohol residue. Correspondingly suitable alkyl radicals are e.g. B. in the dialkyl esters of painting or Fumaric acid called the monomers (ii).

In the manufacture of the polyacrylate polyols know within the above men any proportion of mixtures of the monomers (i) to (iii) are used the, with the proviso that this choice in the preparation of the copolymers so he follows that the resulting copolymers have hydroxyl numbers and glass transition temperatures have structures within the above ranges. This for the invention Usability of the copolymers advantageous condition is met if the Preparation of the copolymers a suitable ratio of "plasticizing" mono mers, which lead to a lowering of the glass transition temperature of the copolymers "Hardening" monomers which lead to an increase in the glass transition temperature lead to Application arrives. "Plasticizing" monomers are, for example, alkyl esters of Acrylic acid such as B. ethyl acrylate, n-butyl acrylate, isobutyl acrylate and 2-ethylhexyl acrylate. "Hardening" monomers are, for example, alkyl esters of methacrylic acid, such as. B. Methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, Isopro pyl methacrylate, tert-butyl methacrylate, neopentyl methacrylate, isobornyl methacrylate and 3,3,5-trimethylcyclohexyl methacrylate, vinyl aromatics, such as. B. styrene, vinyl toluene and α- Ethyl styrene.

The polyhydroxy polyacrylates are prepared by radical-initiated copolymerization of the abovementioned monomers in suitable organic solvents. The monomers are copolymerized at from 60 to 180.degree. C., preferably from 80 to 160.degree. C., in the presence of radical formers and, if appropriate, molecular weight regulators. At 1013 mbar, the solvents have a boiling point or range within the temperature range from 50 to 150, preferably 75 to 130 ° C. Solvents suitable for the preparation of the copolymers are, for example, aromatics, such as toluene or xylene; Esters such as methyl acetate, ethyl acetate, isopropyl acetate, n-propyl acetate, isobutyl acetate, n-butyl acetate or methyl n-amyl acetate; Ketones such as 2-propanone, 2-butanone, 2-pentanone, 3-pentanone, 3-methyl-2-butanone, 4-methyl-2-pentanone, 5-methyl-2-hexanone or 2-heptanone; Alcohols such as n-butanol, n-pentanol or hexanols; Ethers such as butyl glycol dimethyl or propylene glycol dimethyl ether or any mixture of such solvents. The polyhydroxy polyacrylates can be produced continuously or batchwise. Usually, the monomer mixture and the initiator are metered into a polymerization reactor uniformly and continuously, and at the same time the corresponding amount of polymer is continuously removed. In this way, chemically almost uniform copolymers can be produced. Copolymers which are almost chemically uniform can also be prepared by running the reaction mixture into a stirred kettle at a constant rate without removing the polymer. For example, some of the monomers can also be initially introduced in solvents of the type mentioned and the remaining monomers and auxiliaries can be introduced separately or together into this original at the reaction temperature. In general, the polymerization takes place under atmospheric pressure, but can also be carried out at pressures up to 25 bar. The initiators are used in amounts of 0.05 to 15% by weight, based on the total amount of the monomers. Suitable initiators are conventional radical initiators, such as. B. aliphatic azo compounds such as azodiisobutyronitrile, azo-bis-2-methylvaleronitrile, 1,1-azo-bis-1-cyclohexanenitrile and 2,2'-azo-bis-isobutyric acid alkyl ester, symmetrical diacyl peroxides such as. B. acetyl, propionyl or butyryl peroxide, with bromine, nitro or methoxy groups substituted benzoyl peroxides, lauryl peroxides; symmetrical peroxydicarbonates, e.g. B. diethyl, diisopropyl, dicyclohexyl and dibenzoyl peroxydicarbonate; tert-butyl peroxy-2-ethyl hexanoate, tert-butyl perbenzoate; Hydroperoxides such as tert-butyl hydroperoxide, cumene hydroperoxide, dialkyl peroxides such as dicumyl peroxide; tert-butyl cumyl peroxide or di-tert-butyl peroxide. To regulate the molecular weight of the copolymers, customary regulators can be used in the production. Examples include tert-dodecyl mercaptan, n-dodecyl mercaptan or diisopropylxanthogen disulfide. The regulators can be added in amounts of 0.1 to 10% by weight, based on the total amount of the monomer. To isolate the solvent-free polyhydroxy polyacrylates, the solutions obtained are subjected to a solvent removal process, the solvent being removed as completely as possible. Such a solvent removal process can e.g. B. be: spray drying, degassing in special or commercially available evaporation extruders or snake tube evaporators, distillation in vacuum or high vacuum. Alternatively, the polyhydroxy polyacrylates can also be prepared in bulk in the absence of solvents of the type mentioned and discharged and packaged as a hot melt. In such a process, part of the monomers, preferably dialkyl maleic acid, is initially introduced and the remaining monomers and the initiator are introduced separately or together into this template at the reaction temperature, which is preferably in the range from 140 to 180.degree. The finished polymer is discharged as a melt from the reactor, cooled and then granulated.

• 1. Implementation of suitable carboxyl-functional polyacrylates with corresponding sub substituted monoepoxides such. B. isobutylene oxide (2-methyl-1,2-epoxypropane), isoamylene oxide (2-methyl-2,3-epoxybutane), neohexene oxide (3,3-dimethyl-1,2-epoxybutane), cis- and / or trans-2,3-butylene oxide and cyclohexene oxide (1,2-epoxycyclohexane). The implementation Such epoxides with carboxyl-functional polyacrylates are generally made at tem temperatures from 80 to 200 ° C, preferably 100 to 180 ° C with the help of Kataly sators. The reaction is expedient because of the low boiling points of the epoxides in Pressure reactors carried out under pressures up to 20 bar. Suitable catalysts are for example salts of tert. Ammonium compounds such as B. Tetrabutylammonium chloride or tetrabutylammonium bromide.

The carboxyl-functional polyacrylates required are produced in the same way as the aforementioned hydroxyl-functional polyacrylates with the difference that none OH-functional monomers are used. Thereby as carboxyl-functional monomers, preferably acrylic acid or methacrylic acid, however, half-esters of maleic acid and fumaric acid can also be used. A special variant of the production of carboxyl-functional polyacrylates starts from cyclic anhydride groups containing polyacrylates, which using Maleic anhydride are produced, which in a second reaction step  monofunctional alcohols with 1 to 17 carbon atoms, optionally in the presence from Z. B. amine catalysts to the corresponding half ester.

In addition to carboxyl- and / or anhydride-functional monomers, other non-functional comonomers to be used are in principle the same representatives that have already been mentioned as examples in the previously described hydroxy-functional polyacrylates.

• 1. Implementation of suitable epoxy-functional polyacrylates with monocarboxylic acids such as B. acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, iso valeric acid, ethyl methyl acetic acid, trimethyl acetic acid and 2-ethyl hexanoic acid. Prince longer-chain carboxylic acids with up to 17 carbon atoms are also suitable, however, the epoxy-functional polyacrylates to be converted must then be correspondingly high Have glass transition temperatures, so after the reaction with monocarboxylic acids Polyhydroxypolyacrylates with glass transition temperatures result in the desired Range from 30 to 120 ° C.
• 2. Implementation of suitable hydroxy-functional polyacrylates with diisocyanates and correspondingly substituted aliphatic and / or cycloaliphatic diols. Suitable Hydroxy-functional polyacrylates are, for example, those as previously mentioned under 1. called and also those that have primary hydroxyl groups instead of secondary sen. Here are primary hydroxyl polyacrylates that z. B. by Ver Using hydroxyethyl (meth) acrylate as an OH monomer can be produced, preferred. Suitable comonomers have already been mentioned under 1. Suitable for the implementation Diisocyanates are those mentioned in the preparation of the polyhydroxypolyurethanes under (b) Compounds, suitable aliphatic and / or cycloaliphatic diols with secondary and / or tertiary-bonded OH groups are those in the first exemplary group below (a1) listed compounds. According to the invention obtainable in this way Suitable polyhydroxy polyacrylates, the manufacturing process corresponds to that of Preparation of the processes described for polyhydroxypolyurethanes.

The binder components A described below can also be used. As powder component A, the powder coating slurnes of the invention can at least

• 1. a hydroxyl-containing acrylate copolymer (A1) with a glass over transition temperature of 40 to 85 ° C, preferably 45 to 75 ° C (measured in each case with the help of differential scanning calometry (DSC)), a number average molecular weight of 1,500 to 30,000 Daltons, preferably 2,500 to 10,000 (gel permeations in each case determined chromatographically using a polystyrene standard), and an OH Number from 60 to 130 mgKOH / g, preferably 100 to 170 mgKOH / g, the Hydroxyl groups of the binder (A1) up to 60%, preferably up to 50%, from primary bound OH groups exist, and / or
• 2. the reaction product of an acrylate copolymer containing carboxyl groups and an epoxy group-containing compound or the reaction product of an epoxide group-containing acrylate copolymer and a compound containing carboxyl groups, the carboxy / epoxy reaction in each case before or during the reaction of the bandage by means of A with the crosslinking agent B.

Suitable binders A are, for example, hydroxyl-containing polyacrylate resins (A1) net by copolymerization of at least one ethylenically unsaturated monomer, which contains at least one hydroxyl group in the molecule, with at least one further ethylenically unsaturated monomer that contains no hydroxyl group in the molecule, can be produced, at least one of the monomers being an ester of acrylic acid or Is methacrylic acid. Suitable hydroxyl-containing polyacrylate resins (A1) are also, for. B. known from DE-A-43 37 430, DE-A-41 13 052 and EP-A-591 362.

Examples of hydroxyl-containing monomers are hydroxyethyl (meth) acrylate, Hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate and hydroxymethylcyclo called hexenyl (meth) acrylate, preferably hydroxyethyl methacrylate, optionally together with other monomers containing hydroxyl groups. As examples of ethylenically unsaturated monomers that do not contain a hydroxyl group in the molecule, who the alkyl ester of acrylic and methacrylic acid, the 1 to 20 carbon atoms in the alkyl radical contain, in particular methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate,  Butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate. Further examples of ethylenically unsaturated monomers that have no hydroxyl groups in the Containing molecule are acid amides, such as. B. acrylic acid and methacrylic acid amide, vinyl aromatic compounds, such as styrene, methyl styrene and vinyl toluene, nitriles, such as Acrylonitrile and methacrylonitrile, vinyl and vinylidene halides such as vinyl chloride and Vinylidene fluoride, vinyl esters such as e.g. B. vinyl acetate and monomers containing carboxyl groups, such as B. acrylic acid and methacrylic acid.

Furthermore, in the powder coating slurry according to the invention, as binder A or as a wide one res binder also the reaction product of an acrylate containing carboxyl groups copolymer and an epoxy group-containing compound or the reaction product from an epoxy group-containing acrylate copolymer and a carboxyl group-containing one Connection are used. The CarboxylEpoxy implementation can before Mixing with the isocyanate group-containing crosslinker, d. H. as binder A the reaction product is used. But it is also possible in the fiction Powder coating slurry according to a mixture of the component containing epoxy groups and to use the carboxyl group-containing component. In this case the Carboxy / epoxy conversion only during the curing of the powder coating, the Carboxy / epoxy reaction then formed hydroxyl groups in situ with the iso cyanate crosslinker react.

For use in the powder coating slurry according to the invention as a binder compo nente A are z. B. epoxy-containing polyacrylate resins suitable by copolymers sation of at least one ethylenically unsaturated monomer, the at least one Contains epoxy group in the molecule, with at least one other ethylenically unsaturated Monomer that contains no epoxy group in the molecule can be produced, at least one of the monomers is an ester of acrylic acid or methacrylic acid. Such epoxy group-containing polyacrylate resins are e.g. B. known from EP-A-299 420, DE-B-22 14 650, DE-B-27 49 576, US-A-4,091,048 and US-A-3, 781,379). Examples of ethylenically unsung Saturated monomers that do not contain an epoxy group in the molecule are already in the Description of the hydroxyl-containing acrylate copolymers called compounds  The epoxy group-containing polyacrylate resin usually has an epoxy equivalent weight of 300 to 2,500, preferably 350 to 700, a number average molecular weight weight (gel permeation chromatography using a polystyrene standard determined) from 1,700 to 20,000, preferably from 2,000 to 10,000, and a glass over transition temperature (TG) from 30 to 80, preferably from 40 to 30, particularly preferably from 40 to 60 ° C (measured using differential scanning calorimetry (DSC)). All about 50 ° C. are particularly preferred. Mixtures of two or two can also be used more acrylic resins are coming. For the implementation with those containing epoxy groups Acrylate copolymers are e.g. B. carboxylic acids, especially saturated, straight-chain, Aliphatic dicarboxylic acids with 3 to 20 carbon atoms in the molecule are suitable. Most notably a dicarboxylic acid with 12 C atoms in the molecule, such as. B. Dodecan-1,12- dicarboxylic acid used. To modify the properties of the finished powder coating Slurries can optionally also use other compounds containing carboxyl groups become. Examples of this are saturated branched or unsaturated straight-chain di- and polycarboxylic acids and polymers with carboxyl groups.

Furthermore, carboxyl groups are also for the production of the powder coatings according to the invention containing polyacrylate resins as binder component A suitable by Copolymerisa tion of at least one ethylenically unsaturated monomer which is at least one Contains acid group in the molecule, with at least one other ethylenically unsaturated Monomer that does not contain an acid group in the molecule can be produced. To be favoured carboxyl group-containing acrylate copolymers with a glass transition temperature of 30 to 80 ° C, preferably 40 to 60 ° C (each measured with the aid of differential scanning calometry (DSC)), a number average molecular weight of 1,700 to 20,000 daltons, preferably 2,000 to 10,000 (in each case determined by gel permeation chromatography under Use of a polystyrene standard), and an acid number of 60 to 180 mgKOH / g, preferably 100 to 170 mgKOH / g.

The epoxy group-containing compound and the carboxyl group-containing compound are Usually used in an amount such that 0.5 to 1.5, preferably 0.75 to 1.25 equivalents of carboxyl groups are present. The amount of  Existing carboxyl groups can be titrated with an alcoholic KOH solution be determined.

In the powder coating slurry according to the invention, the preferred binders A are hydroxyl or carboxyl- or epoxy-containing acrylate copolymers used, which one Vinyl aromatic compound content of less than 50% by weight, especially before added of less than 30% by weight, very particularly preferably from 10 to 25% by weight, in each case based on the total weight of the monomers used.

The above-mentioned hydroxyl- or epoxy- or carboxyl-containing poly Acrylate resins can be obtained by polymerization using generally well known methods be put. It goes without saying that any mixtures of the bin mentioned can also be used demittel A are used.

In the powder coating slurry according to the invention, optionally together with the hydroxyl group-containing binder A based on acrylate, also containing hydroxyl groups Polyester resins are used, which in the usual way from aromatic or aliphatic or cycloaliphatic diols and / or polyols, optionally in combination with monools, and aromatic or aliphatic or cycloaliphatic di- and / or polycarboxylic acids, optionally in combination with monocarboxylic acids. Due to the better resistance to chalking and weathering are preferably aliphatic and / or cycloaliphatic structural components for the production of the polyester resins used. For example, the polyester resins may have been made using Formation of ethylene glycol, propanediol, butanediol, neopentyl glycol, hexanediol, cyclo hexanediol, 4,4'-dihydroxydlcyclohexylpropane-2,2, trimethylolpropane, hexanetriol, Pentaerythritol. Esters of hydroxycarboxylic acids with diols are also further diols suitable, the diols mentioned above can be used as the diol. Examples of hydroxycarboxylic acids are hydroxypivalic acid or dimethylolpropanoic acid. As acids such. B. adipic acid, glutaric acid, acelaic acid, sebacic acid, fumaric acid, Maleic acid, tetrahydrophthalic acid, hexahydrophthalic acid, cyclohexanedicarboxylic acid, Phthalic acid, terephthalic acid, isophthalic acid and trimellitic acid can be used.  

The esterifiable derivatives of the abovementioned polycarboxylic acids are also suitable, such as B. their mono- or polyvalent esters with aliphatic alcohols with 1 to 4-C- Atoms or hydroxy alcohols with 1 to 4 carbon atoms. In addition, the Anhydrides of the above acids are used, if they exist. Suitable Hydroxyl group-containing polyester resins are also e.g. B. known from DE-A-25 47 124 and EP-A-0 408 465.

Correspond to the polyhydroxy polyesters which can be used as binder component A regarding the type of their hydroxyl groups, their OH number and their glass transition temperature The conditions already generally given above for component A. Your mitt The lower molecular weight (which can be calculated from the OH content and OH functionality) lies in space generally at 400 to 10,000, preferably 1000 to 5000. Such polyhydroxy polyesters are accessible in different ways: esterification of acids or acid derivatives of already mentioned above as an example with excess amounts of di- and / or triols with secondary and / or tertiary alcoholic hydroxyl groups already mentioned above exemplified under (a1) type or implementation of suitable carboxyl-functional Polyester with appropriately substituted monoepoxides. In this case, those for Powder coatings known carboxyl-containing polyesters are used and as described above in the manufacture of the polyhydroxy polyacrylates under point 2 suitable monoepoxides mentioned there as examples.

The crosslinking agent component B is monomers known per se Low renal paint polyisocyanates containing primary or secondary aliphatic Carbon atoms bound free isocyanate groups of 5 to 30 wt .-%, preferably 12 to 23 wt .-%, an average NCO functionality of at least 2.1, preferably at least 2.4 and particularly preferably at least 3.0 and containing monomers Diisocyanates with a molecular weight below 300 of maximum 0.5, preferably at most 0.3% by weight. The crosslinking agent component B has preferably a melting point or range between 30 ° C and 120 ° C, however, this is not an imperative since the only thing that matters is that the Com component B is preferably solid below 30 ° C and liquid above 120 ° C.  

The crosslinking agent component B preferably consists of these known per se Conditions corresponding to urethane groups and especially isocyanurate groups having lacquer polyisocyanates. Suitable poly having isocyanurate groups Isocyanates can, as in EP-A-0003765, EP-A-0010589, EP-A-0017998, EP-A-0047452, EP-A-0187105, EP-A-0978614 or EP-A-0330966. Polyisocyanates modified by urethane groups are obtained, for example, by reaction aliphatic diisocyanates with any, polyvalent aliphatic or cycloaliphatic, optionally containing ether groups or ester groups, polyhydric alcohols in the molecular weight range 62 to 1000 while maintaining a NCO / OH equivalent ratio of <2, preferably from 3: 1 to 15: 1, in particular from 3: 1 to 7: 1, at temperatures of generally 60 to 120 ° C. The Removal of the excess monomeric diisocyanate can be by distillation or extractive take place, preferably the monomeric starting diisocyanate by means of a Thin film distillation apparatus within the temperature range of 140 to 200 ° C a pressure between 0.1 and 0.5 mbar is separated off, so that 100% solids containing polyisocyanates with the specified maximum monomer content of <0.5% by weight, preferably <0.3% by weight, can be obtained.

The above are also suitable according to the invention as crosslinking agent component B. Conditions corresponding lacquer polyisocyanates, both urethane and Contain isocyanurate groups. The conditions mentioned above are also suitable gene corresponding lacquer polyisocyanates, both allophanate and isocyanurate have pen, such as those according to German patent application P 43 35 796.2 can be obtained. Generally speaking, the crosslinking agent Component B from the following exemplified aliphatic and cycloaliphatic Diisocyanates, or mixtures thereof, are obtained by oligomerization, by the production of isocyanurates, biurets, allophanates with mono- and Polyalcohols, carbodiimides or urethanes of polyalcohols. It can too Mixtures of such oligomers can be used.  

Starting diisocyanates for the preparation of crosslinking agent component B are aliphatic diisocyanates in the molecular weight range 140 to 300, 1-isocyanato 3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), 4,4'-diisocyanato dicyciohexylmethane (HMDI) and their mixtures with 1,6-diisocyanatohexane (HDI) are preferred. M-TMXDI (1,3-bis- (2-isocyanatoprop-2-yl) benzene) is also suitable. The starting materials used for the preparation of the lacquer polyisocyanates Diisocyanates can optionally be mixtures and are particularly preferred 70 to 100% by weight of IPDI and / or HMDI and 0 to 30% by weight of HDI. Also Mixtures of appropriate composition of IPDI and HMDI homotrimerizates with HDI homotrimerizates are suitable as component B.

Usually up to 30, preferably up to 20 and in particular are used for the deactivation in particular up to 10 mol% of the total isocyanate groups present with the Desakti cross-linking agent reacted. It is essential that so many reacted that a waterproof encapsulation is created. The lower value can therefore be from Specialist for each individual case can be easily determined using simple preliminary tests.

It is essential for the present invention that the reaction is carried out in water becomes.

Examples of possible deactivating agents are: water, primary and secondary Mono-, di- and polyamines, hydrazine derivatives, amidines, guanidines, mono- and polyal alcohols and compounds containing carboxyl groups, phenolic hydroxyl groups, Contain amide groups or hydrazide groups. Examples of suitable ones Deactivating agents are also those in EP-B-100508 in column 6, lines 10 to 37, and Column 6, line 53 to column 7, line 19, and EP-B-100507, column 5, lines 20 to 58, compounds mentioned and those in EP-A-431 413, DE-A-35 17 333, DE-A- 32 30 757, DE-A-35 29 530, DE-A-34 03 500 and EP-A153 579 Deactivating agent. Regarding further details of the deactivation for example to EP-A-62 780, pages 6 and 7, EP-B-100508, columns 6 and 7, as well as EP-B-100517, column 5. Are also particularly suitable  Deactivating agents, as described in US Pat. No. 4,888,124, column 5, line 60, to Column 7, line 53, are indicated, to which express reference is hereby made.

The function of the deactivating agent can also include specific additives or binders tel constituents, in particular also paint additives added to the aqueous phase, such as Stabilizers, emulsifiers or thickeners take over, unless these substances in the Dispersion particles diffuse in with the consequence of swelling and / or coagulation. A particularly stable dispersion is achieved when at least part of the Stabilizers or emulsifiers is replaced by stabilizers that match those on the upper Surface of the dispersion particles existing NCO groups react and in this respect a Exercise a double function, namely as a deactivating agent. To be favoured those substances selected from the above group that are not only selective with surface NCO groups react, but also a stabilization of the dis Generate persion in water, but ensure that after application and Evaporation of the water during the first stoving or film formation phase, the par Effectively flow the particles and produce smooth, homogeneous, clear films.

In the case of optionally to accelerate the curing of the powder coating resins The catalysts used are, for example, the usual ones from the Po Compounds known to lyurethane chemistry, as already mentioned above in the process for the preparation Position of the polyhydroxypolyurethanes for catalyzing the urethanization reaction, for example were listed. If catalysts are used, are within them Group of zinc, tin (II) or tin (IV) salts preferred. Other representatives of suitable Catalysts as well as details about the operation of such catalysts are in the plastic manual, volume VII, edited by Vieweg and Höchtlen, Carl- Hanser publishing house, Munich 1966, z. B. on pages 96 to 102. The Catalysts can optionally be used in amounts of 0.01 to 5.0% by weight, preferably 0.05 to 1.0 wt .-% based on the total amount of organic binder, d. H. the Combination of components A and B but excluding those if necessary used further auxiliaries and additives.  

In addition, the solid components A and / or B auxiliaries and additives Contain generally defined type above. An example of a degassing agent is Benzoin. Substances based on polyacrylates, polysiloxanes or Fluorine compounds suitable. Antioxidants that can be used are reducing agents such as Hydrazides and phosphorus compounds and radical scavengers such. B. 2,6 di-tert-butylphenol. UV absorbers that can be used are preferably triazines and benzotriphenol. As a radical scavenger 2,2,6,6 tetramethylpiperidine derivatives can be used.

The aqueous phase of the powder coating slurry can contain at least one nonionic thickener. Non-ionic associative thickeners are preferably used. Structure features of such associative thickeners are:

• a) a hydrophilic framework that ensures sufficient water solubility and
• b) hydrophobic groups leading to an associative interaction in the aqueous medium are capable.

Long-chain alkyl radicals, such as, for. B. dodecyl, Hexadecyl or octadecyl residues, or alkaryl residues, such as. B. octylphenyl or nonyl phenyl radicals used. The preferred hydrophilic frameworks are polyacrylates, Cellulose ethers or particularly preferably polyurethanes are used, which are hydrophobic Contain groups as polymer building blocks. Are particularly preferred as hydrophilic Frameworks, preferably containing polyether chains as building blocks Polyethylene oxide. In the synthesis of such polyether polyurethanes, the di- and or serve Polyisocyanates, preferably aliphatic diisocyanates, particularly preferably optionally alkyl Substituted 1,6-hexamethylene diisocyanate, for linking the hydroxyl group termi nated polyether building blocks with each other and to link the polyether building blocks with the hydrophobic end group building blocks, for example monofunctional alcohols and / or amines with the long-chain alkyl radicals or aralkyl radicals already mentioned can. Furthermore, the aqueous phase can contain catalysts, leveling agents, antioxidants, Contains UV absorbers, radical scavengers and wetting agents. In essence, here come the substances already listed for components A and / or B. Can also the aqueous phase auxiliaries, defoamers, dispersion aids, biocides, Solvents and neutralizing agents must be added. As defoaming agents come  preferably modified polysiloxanes. Dispersion aids are e.g. B. preferred Ammonium or metal salts of polycarboxylates. Suitable neutralizing agents are amines and metal hydroxides.

The binder A and also the crosslinking agent B may so that the Application and film properties of the powder coating slurry even after long storage do not change the material, neither at room temperature nor with each other added additives or the water acting as a solvent react.

The powder coating slurry according to the invention is different in the powder coating slurry Technology usual processes can be produced.

In the process according to the invention, however, the binder components A and the crosslinking agent component B is discharged as solids after their synthesis and then in the usual and known manner in the molten state with the aid of Kneaders or extruders homogenized, if necessary using a vacuum of organic solvents are freed.

It is essential for the process according to the invention that the homogenization is so it is widely promoted that not less than 30, preferably not less than 60 and in particular not less than 90% by weight of the polyisocyanate B in which the binders A containing particles are dispersed or dissolved.

According to the invention, the polyisocyanates B and the binders are present in the particles. For practical reasons, however, less than 100% of the polyisocyanates B in the Particles may be included. They then form particles, which form a discrete separate phase available. It is essential that not less than 30%, preferably not less than 90% of the polyisocyanates B are contained in the particles which contain the binder A.

After homogenization, the particles are up to an average grain size of 80 to Grind 100 µm using standard methods. Then the resulting powder is under  Addition of the deactivating agent and, if appropriate, addition of further additives and if necessary in several steps with water (deionized) and by means of wet grinding (see, for example, patent specification DE 196 13 547 A1) ver to an average grain size of <10 μm grind. Instead, the water can use all or only some of the additives contain.

The powder coating slurry according to the invention advantageously has a proportion of under Ver volatile organic components of less than 1.5%. They don't volatile fractions are advantageously in the range from 25 to 55% by weight, preferably of 30 and 45% by weight. The powder slurry according to the invention is used for the application Water and / or adjusted with thickener to the appropriate spray viscosity.

The powder coating slurry according to the invention can be in the form of a pigmented coating or in the form of a coating a clear lacquer as a coating of decorative basecoats, preferably in the automobile industry, use. The powder coating slurries according to the invention can be used with the apply methods known from liquid coating technology. In particular, they can be applied by spraying. There are also electrostatically assisted ones Rotation or pneumatic application into consideration. The on a (decorative) basis Powder clearcoat slurries are regularly applied before baking vented. This is expediently done first at room temperature and / or at slightly elevated temperature. As a rule, the elevated temperature is 40 to 70 ° C preferably 50 to 65 ° C. Flash off for 2 to 20 minutes, preferably 4 to 8 minutes. It can also be initially above room temperature at room temperature Period of time are flashed off and then at the elevated temperature mentioned. At the elevated temperature is then flashed off again during the same time period. The Baking can be carried out at temperatures of 130 ° C. Feasible is the baking at 130 to 180 ° C, preferably 135 to 145 ° C, and over a Period of 10 to SO min., Preferably 12 to 30 min. The application of powder paint Slurry is preferably carried out in an amount such that after baking a layer thickness of resulting coating layer of 30 to 50 microns, preferably 35 to 45 microns, is achieved. These layer thicknesses are sufficient to obtain a high-gloss clear coat film  In terms of durability, a MEK resistance of more than 100 double strokes and good condensation resistance.

Claims (11)

1. powder coating slurry, in particular powder clear coating slurry, containing at least one hydroxyl-containing binder A, at least one polyisocyanate as crosslinking agent B and water, characterized in that

• 1. the hydroxyl-containing binder A and the polyisocyanate B are homogenized in such a way that not less than 30, preferably not less than 60 and in particular not less than 90% by weight of the polyisocyanate B are dispersed or dissolved in the particles containing the binder A and
• 2. The particles of the crosslinking agent B, which may still be in the aqueous phase, and the particles which contain the binders A and crosslinking agent B, are stabilized via the isocyanate groups present on their surface by means of a deactivating agent added to the aqueous phase.

2. Powder coating slurry according to claim 1, characterized in that the components A and B are used in a quantity ratio with the proviso that OH groups and NCO groups in an OH: NCO molar ratio of 0.6: 1 to 1: 1.4, preferably 0.8 to 1: 1.2. 3. powder coating slurry according to claim 1 or 2, characterized in that usual Paint additives, in particular degassing agents, leveling agents, light stabilizers such as UV absorbers and radical scavengers, defoamers, antioxidants and Stabilizers are included. 4. Powder coating slurry according to one of claims 1 to 3, characterized in that ent at least one catalyst for the reaction of OH groups with NCO groups hold is.   5. Powder coating slurry according to one of claims 1 to 4, characterized in that the binder A contains:

• 1. 50-100% by weight. preferably 66-100% by weight of a polyhydroxy polyacrylate a,
• 2. 0-50 wt .-%, preferably 0.1 to 34 wt .-%, of one or more of a) different binders from the group of polyols, poly hydroxypolyurethanes, polyhydroxy polyesters or polyepoxides.

6. powder coating slurry according to claim 5, characterized in that the poly hydroxypolyacrylate a is obtainable by reacting

• 1. 7 to 60% by weight of hydroxyalkyl (meth) acrylates with primary, secondary and / or tertiary OH groups,
• 2. 40-93% by weight (cyclo) alkyl ester of (meth) acrylic acid with 1 to 18 carbon atoms in the (cyclo) alkyl radical,
• 3. 0-10% by weight (meth) acrylic acid,
• 4. 0-30% by weight, preferably 0-10% by weight, of multiple (meth) acrylic acid esters of polyalcohols,
• 5. 0-40% by weight, preferably 0-35% by weight of different comonomers from a1 to a4,

wherein the sum of the parts by weight of components a1 to a5 is 100%, component a1 being selected with the proviso that at least 40% of the OH groups of polyhydroxypolyacrylate a are bound to secondary or tertiary carbon atoms and wherein polyhydroxypolyacrylate a an OH number from 30 to 200, preferably from 70 to 170, an acid number from 0 to 50, preferably from 0 to 35, an average molecular weight (number average, determined by means of the GPC method against polystyrene standard) from 1500 to 30,000, preferably from 1700 to 18000, and a glass transition temperature of 40 to 85 ° C, preferably from 45 to 75 ° C, has. 7. powder coating slurry according to one of claims 1 to 6, characterized in that the Crosslinking agent B has an NCO content of 5.0 to 30% by weight, preferably 12 up to 23% by weight, with an average NCO functionality of at least 2.1, preferably of at least 2.4, and containing monomeric diisocyanates has a molecular weight of less than 300 of less than 1.5 wt .-%, and that Crosslinking agent B a glass transition temperature of 40 to 150 ° C, preferably 50 to 135 ° C. 8. powder coating slurry according to any one of claims 1 to 7, characterized in that one or more crosslinking agents different from crosslinking agent B. from the group of amino resins, carbamate resins and blocked polyisocyanates in one Amount up to 60 wt .-% of the crosslinking agent B is or are. 9. powder coating slurry according to any one of claims 1 to 8, characterized in that as Deactivating agent one or more substances from the group alcohols, OH functional polyethers, monoanines, polyarnines, OH-functional amines, NH-functio nelle polyether and OH- and NH-functional polyether is or will be used. 10. A process for producing the powder coating slurry according to any one of claims 1 to 9, by homogenizing the binder A and the crosslinking agent B, grinding the resulting mixture and wet grinding the resulting powder to an average grain size below 10 microns, characterized in that

• 1. the hydroxyl-containing binders A and the polyisocyanates B are homogenized to such an extent that not less than 30, preferably not less than 60 and in particular not less than 90% by weight of the polyisocyanate B are dispersed or dissolved in the particles containing the binder A, and
• 2. The particles of the crosslinking agent B which may still be in the aqueous phase and the particles which comprise the binders A and the crosslinking agent B are stabilized by means of the isocyanate groups present on their surface by means of a deactivating agent added to the aqueous phase.

11. Use of the powder coating slurry, according to one of claims 1 to 9 or according to Claim 10 produced powder coating slurry for the production of a coated Substrate, in particular a motor vehicle body or a motor vehicle body part, wherein on the substrate, if necessary after applying a primer and / or a filler, a de applied top coat and then after drying the pulp clear varnish slurry is applied with conventional spray application devices and the topcoat and the powder clearcoat possibly after a further predrying be branded together.